In a slitting line, relatively wide strip is cut in to a number of relatively narrower widths usually by pulling the strip through a slitter. The slitter includes parallel arbors on which the slitting knives are positioned. Usually the top arbor is positioned by hydraulically operated jacks to be moved in parallelism with the bottom arbor to control the vertical spacing of the cooperating knives.
The slitting knives may be placed on the arbors at any desired location to control the number and widths of the slit strip. However, if variations are desired in the number and widths of the slit strip, or if the grade or gage of the metal strip changes, the spacing of the knives on the arbors may require to be changed. Such variations occur frequently and to change the set up of the knives usually requires partial disassembly of the slitter to expose the ends of the arbors so that the knives and spacers may be removed and replaced. The set up of the slitting knives is a time consuming operation and if the set up is done at the slitting line, it requires that the slitting line be down or inoperative for an inordinate length of time.
This problem has to some extent been obviated by the use of slitting lines employing multiple heads. The heads may be mounted on a turret and the heads rotated into and out of operative position. Reference may be had to U.S. Pat. Nos. 3,513,743 and 3,727,503 for illustrations of multiple head slitters utilizing a turntable. PG,3 Such turret arrangements, however, require a significant capital investment which must be balanced against the down time of the slitting line to make set-up changes. Moreover, when hydraulically operated jacks are employed which must be connected and disconnected during set-up changes, additional down time is required both to disconnect the jacks and any electrical or hydraulic lines involved and also to reset the jacks with the aid of a counter or other suitable mechanism to insure proper arbor parallelism. If the jacks are disconnected, they must usually be carefully reset because of the backlash in the gearing employed.
In many slitting operations space is a significant obstacle and it may not be possible or desirable to retool the slitter at the slitting line. It may be more desirable to retool the slitter at a work area or bench where an inventory of knives and spacers are conveniently kept. Most slitting operations include an overhead crane and it is accordingly desirable to have a removable slitter head which can be conveniently lifted to another location for retooling and returned when desired. However, a crane in a slitting operation has many other uses and it may be available precisely when desired. Accordingly, a slitter head which can quickly be removed to and replaced from a lift off or storage position is highly desirable.
If multiple slitter heads are employed, it is important that they be as simple or inexpensive as possible and that they can be connected and disconnected from the slitter as quickly as possible.